BBC Health Correspondent, Essex
A mental health trust has admitted that its failure to care for the 16-year-old hospitalization resulted in her death.
Harry Potter fan and music lover Elise Sebastian found no response in a room at the St Auburn Center unit in Colchester in April 2021.
The unit’s employees are operated by Essex Partnership University NHS Foundation Trust (EPUT) and are responsible for providing one-to-one care.
The family participated in the first day of her death inquiry, where they were conducting a public survey of Lampard, which is investigating more than 2,000 deaths.
The Lampard query team will monitor Ms. Sebastian's investigation.
The Essex Coroner Court investigation heard how Elise should have one-on-one care in St Aubyn units after several attempts to self-harm.
Essex Regional Coroner Sonia Hayes said she should be observed when she was in an isolated area.
Victoria Sebastian's mother visited Elise on April 17 of that year and gave her a hug.
However, when she left, Elise was allowed to enter her bedroom from the public area without staff.
The teenager lives in Nanyue near Malden and was found unresponsive and died in the hospital two days later.
Mrs. Sebastian told the Investigation that her death was “too much to bear” and that Ellis was “severely disappointed by the system.”
Eput accepted the failure of the trust as "the cause of her death," said Pravin Fernando, its attorney, "[It]allowed her to go to the bedroom without supervision, thus failing."
The family also said Eput staff didn't tell them where Elise was after she was taken to the hospital - so they drove to Colchester Hospital and hoped she was there.
Michael Lewis, a senior paramedic at the NHS Trust, an ambulance service in East England, was called upon after finding Elise was not responding.
He said he encountered several locked doors and became "very frustrated."
"I don't think anyone is responsible there," he said.
"Every problem has been encountered 'I don't know'."
He continued: "I was told that the patient was in a one-on-one observation, so I remember thinking - how this happened."
Dr. Lisa Cunningham, an emergency medicine consultant for Essex County Air Ambulance, said in a statement that “there is pressure on staff”.
Mrs. Sebastian said the family meant everything to Ellis, who had a wonderful relationship with her brother and two sisters.
Her father, Glen Sebastian, described her as a “typical little princess” and said they would enjoy visiting places like the West Side and the Art Gallery.
He said: "She will blow me up with her paintings, and of course she has a gift."
Ms. Hayes heard about how Ellis was diagnosed with autism and sometimes struggled to understand other people’s behavior.
She has physical health problems, including intestinal problems and spinal curvature.
The teenager was also diagnosed with epilepsy, which affected her confidence in her social interaction.
The coroner was told that she first struggled with anxiety at the age of 12 and received several admissions from the Mental Health Force when she was 15 after bullying.
She managed to abscond on a previous occasion.
The Sebastian couple, who are now separated, both said they have suffered from PTSD since her death.
Ms. Hayes said in her opening remarks: “A young man with his own hope and dream.”
The investigation is expected to last four weeks.